allow $if work everywhere

[kbkpbot]

Describe the feature

$if conditional compile can work only on some code regions.

Use Case

some use case :

module main

$if x64 { 
	pub type Digits = u64
} 
$else {
	pub	type Digits = u32
}


fn main() {
	y := []Digits{}
	dump(y)
}

Proposed Solution

Generate #ifdef at $if.

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

Version used

V 0.4.9 ab2eb00.2cd1f6e

Environment details (OS name and version, etc.)

V full version	V 0.4.9 ab2eb00.2cd1f6e
OS	linux, Ubuntu 24.04.2 LTS
Processor	8 cpus, 64bit, little endian, Intel(R) Core(TM) i7-9700 CPU @ 3.00GHz
Memory	11.79GB/15.51GB
V executable	/media/HD/github/kbkpbot/v/v
V last modified time	2025-03-01 11:56:45
V home dir	OK, value: /media/HD/github/kbkpbot/v
VMODULES	OK, value: /home/mars/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /media/HD/github/kbkpbot/v
Git version	git version 2.43.0
V git status	weekly.2025.09-24-g2cd1f6e9
.git/config present	true
cc version	cc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
gcc version	gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
clang version	Ubuntu clang version 18.1.3 (1ubuntu1)
tcc version	tcc version 0.9.28rc 2024-07-31 HEAD@1cee0908 (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 0134e9b9-dirty
emcc version	N/A
glibc version	ldd (Ubuntu GLIBC 2.39-0ubuntu8.4) 2.39

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[huly-for-github]

Connected to Huly®: V_0.6-22241

[larpon]

Hear. We need top level support for comptime logic, also for import statements

[JalonSolov]

... and consts. :-)

[medvednikov]

Yeah I'd like that very much

[enghitalo]

And struct fields...

[medvednikov]

For sure. I actually needed custom struct fields like that a couple of times.

[Wajinn]

Maybe, the extent to which this implemented, could use some caution or be done in steps, to make sure it doesn't cause other unforeseen issues. Sometime too much of a good thing, can be bad for us too.